1. Field of the Invention
This invention relates to an apparatus for automatically mounting electronic parts on a printed circuit board.
2. Description of the Related Art
A known electronic-parts mounting apparatus includes an electronic-parts feeder, a mounting head, and a mounting portion. A printed circuit board is placed in position within the mounting portion. The mounting head carries electronic components (electronic parts) from the electronic-parts feeder to the mounting portion, and mounts the electronic components on the printed circuit board. The mounting portion is provided with an XY table for moving the printed circuit board in two perpendicular directions on a horizontal plane. The XY table is rotatable.
In the known electronic-parts mounting apparatus, the XY table is rotated from a normal position when the actual posture of an electronic component held by the mounting head differs from a desired posture, or when an electronic component is required to be obliquely mounted on the printed circuit board. Specifically, in the case where the actual posture of an electronic component held by the mounting head differs from a desired posture, the electronic component is carried to a place above the printed circuit board in the mounting portion while the actual posture thereof remains different from the desired posture. The XY table is rotated from its normal position to compensate for the error in the posture of the electronic component held by the mounting head. Then, the mounting head is lowered toward the printed circuit board, and the electronic component is mounted thereon by the mounting head.
The postural error compensation using rotation of the XY table causes a long mounting time to be spent per electronic component. The reason for the long mounting time is as follows. The XY table is large and heavy. Therefore, the time interval between the moment of start of rotation of the XY table and the moment of stop thereof is relatively long. After the stop of rotation of the XY table has been completed, the mounting head commences to be lowered toward the printed circuit board. Accordingly, the known electronic-parts mounting apparatus tends to be low in mounting speed or rate.
It is an object of this invention to provide an electronic-parts mounting apparatus having a high mounting speed or rate.
A first aspect of this invention provides an electronic-parts mounting apparatus comprising an electronic-parts feeder; a mounting head for carrying electronic parts from the electronic-parts feeder, the mounting head including a plurality of nozzles for holding the electronic parts respectively; an electronic-parts mounting portion for enabling the mounting head to mount the electronic parts on a circuit board; first means for rotating each of the nozzles; and second means for moving each of the nozzles upward and downward.
A second aspect of this invention is based on the first aspect thereof, and provides an electronic-parts mounting apparatus wherein the first means includes a pinion provided on an outer circumferential surface of each of the nozzles, and a rack meshing with the pinion.
A third aspect of this invention is based on the second aspect thereof, and provides an electronic-parts mounting apparatus wherein the rack includes a first rack plate, a second rack plate slidably superposed on the first rack plate, and means for urging the second rack plate relative to the first rack plate in a direction parallel to the first rack plate.
A fourth aspect of this invention is based on the third aspect thereof, and provides an electronic-parts mounting apparatus further comprising third means for urging each of the nozzles in a direction of rotation of the nozzle.
A fifth aspect of this invention is based on the second aspect thereof, and provides an electronic-parts mounting apparatus wherein positions of the nozzles correspond to integer multiples of a pitch of teeth of the rack respectively.
A sixth aspect of this invention is based on the first aspect thereof, and provides an electronic-parts mounting apparatus wherein each of the nozzles includes an outer cylinder, a holder, means for rotatably supporting the outer cylinder on the holder, an inner cylinder extending into the outer cylinder and being movable upward and downward relative to the outer cylinder, a pinion provided on the outer cylinder, and further comprising a rack meshing with the pinion, and means for supporting the rack slidably on the holder.
A seventh aspect of this invention is based on the sixth aspect thereof, and provides an electronic-parts mounting apparatus wherein each of the nozzles includes a coil spring provided between the outer cylinder and the holder.
An eighth aspect of this invention is based on the first aspect thereof, and provides an electronic-parts mounting apparatus wherein the second means includes a fluid-operated actuator having a piston in engagement with an upper end of each of the nozzles.
A ninth aspect of this invention is based on the eighth aspect thereof, and provides an electronic-parts mounting apparatus further comprising a limiting plate engageable with a lower end of the piston for determining a lower limit position of the piston, a first spring for urging the piston downward, and a second spring for urging the nozzle upward.
A tenth aspect of this invention provides an electronic-parts mounting apparatus comprising an electronic-parts feeder; a mounting head for carrying electronic parts from the electronic-parts feeder, the mounting head including a plurality of nozzles for holding the electronic parts respectively; an electronic-parts mounting portion for enabling the mounting head to mount the electronic parts on a circuit board; first means for rotating each of the nozzles; a fluid-operated actuator for moving each of the nozzles upward and downward, the fluid-operated actuator having a piston in engagement with an upper end of each of the nozzles; a limiting plate engageable with a lower end of the piston for determining a lower limit position of the piston; a first spring for urging the piston downward; a second spring for urging the nozzle upward; and second means for moving the limiting plate upward and downward.
An eleventh aspect of this invention provides an electronic-parts mounting apparatus comprising an electronic-parts feeder; a mounting head for carrying electronic parts from the electronic-parts feeder, the mounting head including a plurality of nozzles for holding the electronic parts respectively; an electronic-parts mounting portion for enabling the mounting head to mount the electronic parts on circuit board; first means for rotating each of the nozzles; a fluid-operated actuator for moving each of the nozzles upward and downward, the fluid-operated actuator having a piston in engagement with an upper end of each of the nozzles, a limiting plate engageable with a lower end of the piston for determining a lower limit position of the piston; a first spring for urging the piston downward; a second spring for urging the nozzle upward; second means for detecting heights of the electronic parts held by the nozzles; and third means for moving the limiting plate upward and downward in response to the heights detected by the second means.
A twelfth aspect of this invention is based on the eighth aspect thereof, and provides an electronic-parts mounting apparatus wherein the second means includes a bearing for rotatably connecting the piston and the upper end of each of the nozzles.